Photoresist polymers

ABSTRACT

The present invention is directed to the preparation of photoresist polymers via living free radical polymerization techniques. Sterically bulky ester monomers are utilized as the polymerization components. Use of chain transfer agents is included in polymerization processing conditions. Cleavage of polymer terminal end groups that include a heteroatom are described.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of International Application No.PCT/US2004/020352, filed 25 Jun. 2004 and published as WO 2005/000924 A1on 6 Jan. 2005, which claims priority to U.S. Provisional PatentApplication Ser. No. 60/483,390 filed Jun. 26, 2003 and claims thepriority thereof, the subject matter of which is hereby incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

Processes for patterning semiconductor wafers typically rely onlithographic transfer of a desired image from a thin-film ofradiation-sensitive resist material. The process entails the formationof a sacrificial layer, the “resist”, which is photo-lithographicallypatterned. Generally these resists are referred to as “photoresists”.

The patterning of the resist involves several steps, including exposingthe resist to a selected light source through a suitable mask to recorda latent image of the mask and then developing and removing selectedregions of the resist. For a “positive” resist, the exposed regions aretransformed to make such regions selectively removable; while for a“negative” resist, the unexposed regions are more readily removable.

The pattern can be transferred into surface texture in the wafer byetching with a reactive gas using the remaining, patterned resist as aprotective masking layer. Alternatively, when a wafer is “masked” by theresist pattern, it can be processed to form active electronic devicesand circuits by deposition of conductive or semiconductive materials orby implantation of dopants.

Materials used in single layer photoresists for optical lithographyshould meet several objectives. Low optical density at the exposurewavelength and resistance to image transfer processes, such as plasmaetching, are two important objectives to be met by such a photoresistmaterial. Shorter wavelengths of radiation permit greater resolution.The most common wavelengths currently used in semiconductor lithographyare 365 nm, 248 nm and more recently 193 nm. The desire for narrowerlinewidths and greater resolution has fueled an interest in photoresistmaterials that can be patterned by even shorter wavelengths of light.

In the field of microfabrication, the processing size has become moreand more minute in order to achieve higher integration. In recent years,development of lithographic processes enabling stable microfabricationwith a line width of 0.5 microns, more preferably 0.2 microns or less,has been of keen interest.

However, it is difficult to form fine patterns with high accuracy usingconventional methods which utilize visible rays (wavelength: 700-400 nm)or near ultraviolet rays (wavelength: 400-300 nm). To address thisproblem, lithographic processes using radiation with a shorterwavelength (wavelength: 300 nm or less) have been developed. Suchshorter wavelength radiation can achieve a wider range of depth of focusand is effective for ensuring design rules with minimum dimensions.

Examples of short wavelength radiation, deep ultraviolet rays, such asthose generated from a KrF excimer laser (wavelength: 248 nm), or an ArFexcimer laser (wavelength: 193 nm) can be utilized as well as X-rayssuch as synchrotron radiation, charged particle rays such as electronbeams and the like. However, the polymeric materials used with suchprocesses are limiting in terms of composition, chemical resistance,transparency to DUV and physical characteristics.

There is a need in the art for novel polymeric materials that aretransparent for use in DUV, to allow penetration of activating light,and that are robust enough to withstand further processing conditions.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the present invention provides polymers having theformula

wherein R¹ represents a hydrogen atom or a methyl group, each R²,individually, represents a linear or branched, non-substituted orsubstituted, alkyl group having 1-4 carbon atoms or a bridged ornon-bridged, non-substituted or substituted, monovalent alicyclichydrocarbon group having 4-20 carbon atoms, provided that at least oneR² group is a linear or branched alkyl group having 1-4 carbon atoms, orany two R² groups form, in combination and together with the carbonatoms to which the two R² groups bond, a bridged or non-bridged,non-substituted or substituted, divalent alicyclic hydrocarbon grouphaving 4-20 carbon atoms, with the remaining R² groups being a linear orbranched, non-substituted or substituted, alkyl group having 1-4 carbonatoms or —C(R₂)₃ is one of

and

wherein the polymer is prepared by a living free radical process in thepresence of a chain transfer agent (CTA) having the formula

wherein R^(x) is a group that is sufficiently labile to be expelled asits free radical form, T is carbon or phosphorus, and Z is any groupthat activates the C═S double bond towards a reversible free radicaladdition fragmentation reaction.

In certain embodiments, Z is selected from the group consisting ofhydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl,substituted heteroatom-containing hydrocarbyl, and combinations thereof.

In other embodiments, Z is selected from the group consisting ofhydrogen, optionally substituted alkyl, optionally substituted aryl,optionally substituted alkenyl, optionally substituted acyl, optionallysubstituted, aroyl, optionally substituted alkoxy, optionallysubstituted heteroaryl, optionally substituted heterocyclyl, optionallysubstituted alkylsulfonyl, optionally substituted alkylsulfinyl,optionally substituted alkylphosphonyl, optionally substitutedarylsulfinyl, and optionally substituted arylphosphonyl.

In a further aspect, the polymeric resins of the invention can furtherinclude at least a second recurring unit having the formula

wherein R³ represents a hydrogen atom or a methyl group, R⁴ is a linearor branched alkyl group having 1-6 carbon atoms or a linear or branchedalkyl group having 1-6 carbon atoms substituted with one or morealkyloxy, alkylcarbonyloxy or oxo groups, two or more R⁴ groups, ifpresent, being either the same or different, i is an integer of 0−(3+k),j is 0 or 1, k is an integer of 1-3, R⁵ represents a hydrogen atom or amethyl group, B is a methylene group, an oxygen atom, or a sulfur atom,R⁶ represents a hydrogen atom, a linear or branched alkyl group having1-6 carbon atoms, or a linear or branched alkyl group having 1-6 carbonatoms substituted with one or more alkyloxy, alkylcarbonyloxy or oxogroups, R⁷ represents a hydrogen atom or a methyl group, and R⁸represents a hydrogen atom, a linear or branched alkyl group having 1-6carbon atoms, or a linear or branched alkyl group having 1-6 carbonatoms substituted with one or more alkyloxy, alkylcarbonyloxy or oxogroups.

The polymeric resins of the present invention can further include atleast one additional recurring unit having the formula

wherein where E represents a group derived from non-bridged or bridged,non-substituted or substituted alicyclic hydrocarbons and R⁹ is ahydrogen atom, trifluoromethyl or a methyl group.

The polymeric resins of the invention generally have a molecular weightof between about 2,000 and about 30,000. Additionally, the polymericresins generally have a polydispersity is less than or equal to about1.5. Lastly, the polymeric resins that are prepared by the methods ofthe invention generally include a CTA fragment that can be cleaved bymethods disclosed throughout the specification.

In another aspect, the present invention pertains to a polymer havingthe formula[A]_(x)[B]_(y)[C]_(z)  (I)

wherein A, B and C are each individually one of

More particularly, “x” is between about 0 and about 200 inclusive, “y”is between about 1 and about 200 inclusive and “z” is between about 1and about 200 inclusive. In general, the polymers of the invention arerandom copolymers and can be prepared in a batch process or undersemi-continuous polymerization reaction conditions.

In certain aspects of the polymers of the invention, x has a value of atleast 1.

In other aspects of the invention, the polymers of the invention have apolydispersity index of less than about 1.7 and more specifically arebetween about 1.2 and about 1.4. Molecular weights (M_(w)) of thepolymers of the invention have a range of from between about 2,000 toabout 30,000.

In one embodiment, A, B and C, each individually, are selected from

and x is at least one (1). In a specific embodiment, A, B and C are eachdifferent (A≠B≠C). For instance, an exemplary polymer prepared withthree different methacrylic monomers (A, B and C) is

(II). It should be understood by one skilled in the art, that in thepolymeric formula [A]_(x)[B]_(y)[C]_(z), monomeric subunits of A, B andC have been polymerized through their respective unsaturated olefinicportions into a resultant polymeric resin.

In another embodiment, A, B and C, each individually, are selected from

where x is at least one (1). For example, a polymer prepared from threedifferent acrylic monomers (A, B and C) can be represented by thepolymeric resin as

(III). Therefore, both acrylic and methacrylic type esters havingsterically bulky ester groups have been prepared and are encompassed bythe present invention and are useful, for example, in coatingsapplications, e.g., photoresist materials.

In still another embodiment, A, B and C, each individually, are selectedfrom

where x is at least one (1). For example, a polymer prepared from threedifferent acrylic monomers (A, B and C) can be represented by thepolymeric resin as

(IV). Therefore, both acrylic and methacrylic type esters, and mixturesthereof, having sterically bulky ester groups have been prepared and areencompassed by the present invention and are useful, for example, incoatings applications, e.g., photoresist materials.

In certain aspects of the invention, the terminal end position of thepolymer (acrylic or methacrylic derivatives) includes a thiocarbonylthiomoiety. The thiocarbonylthio moiety can be also be subjected to cleavageconditions so that in one embodiment, the terminal end position of thepolymer includes a termination group having the formula

wherein R′ is CN or COOMe. Alternatively, the terminal position can becapped by a hydrogen atom, a monomeric unit or with a RAFT groupdepending upon the conditions selected.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. As will be realized, theinvention is capable of modifications in various obvious aspects, allwithout departing from the spirit and scope of the present invention.Accordingly, the drawings and detailed description are to be regarded asillustrative in nature and not restrictive.

DETAILED DESCRIPTION

High absorption at 193 or 157 nm limits the light penetration into theresist and does not allow for complete resist exposure at the bottom ofthe resist. Without complete resist exposure, the resist cannot imageproperly. If the resist is made thin enough to ensure full exposure, itmay not be sufficiently thick to withstand subsequent processing stepssuch as plasma etching or ion implantation. To compensate for thisproblem, resist designers often resort to multilayer resists in which asufficient thin resist is deposited on top of a second resist that ismore photoreactive. While these composite resists are effective,resolution is compromised by the undercutting or widening of the exposedareas during development. The present invention provides materials andmethods to produce single or multilayer thin resists that aresufficiently thin so as to permit light to penetrate to the bottom ofthe resist while also being sufficiently thick enough to withstandetching and/or other post exposure processing steps. Conventionalaqueous developers can be used to remove the exposed base solublepolymer after exposure to the radiant energy source.

The ability to form a photolithographic pattern is defined by Rayleigh'sequation in which R represents a resolution or line width of an opticalsystem. Rayleigh's equation is:R=kλ/NA

wherein λ represents a wavelength of an exposure light, NA is anumerical aperture of a lens, and k is a process factor. It should beunderstood from the Rayleigh equation that a wavelength λ of an exposurelight must decrease in value in order to accomplish a higher resolutionor obtain a smaller R. For example, it is well known that a highpressure mercury vapor lamp emits a defined band of radiation (the“i-line”) at a wavelength of 365 nm. Mercury vapor lamps have been usedas a light source for manufacturing a dynamic random access memory(DRAM) having an integration equal to or smaller than 64M bits.Similarly, the KrF excimer laser emitting radiant energy at a wavelengthof 248 nm is commonly used in a mass production of 256 bit DRAM devices.This manufacturing process requires a processing dimension smaller than0.25 microns. Even shorter wavelengths are required for themanufacturing of DRAMs having an integration higher than 1 G bits. Suchdevices will require a processing dimension smaller than 0.2 microns.For this purpose, other excimer lasers such as the KrCl laser having awavelength of 222 nm, the ArF laser having a wavelength of 193 nm and,the F₂ laser having a wavelength of 157 nm, are currently beinginvestigated.

In one aspect, the present invention provides polymers having theformula

wherein R¹ represents a hydrogen atom or a methyl group, each R²,individually, represents a linear or branched, non-substituted orsubstituted, alkyl group having 1-4 carbon atoms or a bridged ornon-bridged, non-substituted or substituted, monovalent alicyclichydrocarbon group having 4-20 carbon atoms, provided that at least oneR² group is a linear or branched alkyl group having 1-4 carbon atoms, orany two R² groups form, in combination and together with the carbonatoms to which the two R² groups bond, a bridged or non-bridged,non-substituted or substituted, divalent alicyclic hydrocarbon grouphaving 4-20 carbon atoms, with the remaining R² groups being a linear orbranched, non-substituted or substituted, alkyl group having 1-4 carbonatoms or —C(R₂)₃, is one of

such that the

indicates that the bond carbon bond is directly attached to the esteroxygen; and

wherein the polymer is prepared by a living free radical process in thepresence of a chain transfer agent (CTA) having the formula

wherein R^(x) is a group that is sufficiently labile to be expelled asits free radical form, T is carbon or phosphorus, and Z is any groupthat activates the C═S double bond towards a reversible free radicaladdition fragmentation reaction.

In certain embodiments, Z is selected from the group consisting ofhydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl,substituted heteroatom-containing hydrocarbyl, and combinations thereof.

In other embodiments, Z is selected from the group consisting ofhydrogen, optionally substituted alkyl, optionally substituted aryl,optionally substituted alkenyl, optionally substituted acyl, optionallysubstituted, aroyl, optionally substituted alkoxy, optionallysubstituted heteroaryl, optionally substituted heterocyclyl, optionallysubstituted alkylsulfonyl, optionally substituted alkylsulfinyl,optionally substituted alkylphosphonyl, optionally substitutedarylsulfinyl, and optionally substituted arylphosphonyl.

In a further aspect, the polymeric resins of the invention can furtherinclude at least a second recurring unit having the formula

wherein R³ represents a hydrogen atom or a methyl group, R⁴ is a linearor branched alkyl group having 1-6 carbon atoms or a linear or branchedalkyl group having 1-6 carbon atoms substituted with one or morealkyloxy, alkylcarbonyloxy or oxo groups, two or more R⁴ groups, ifpresent, being either the same or different, i is an integer of 0−(3+k),j is 0 or 1, k is an integer of 1-3, R⁵ represents a hydrogen atom or amethyl group, B is a methylene group, an oxygen atom, or a sulfur atom,R⁶ represents a hydrogen atom, a linear or branched alkyl group having1-6 carbon atoms, or a linear or branched alkyl group having 1-6 carbonatoms substituted with one or more alkyloxy, alkylcarbonyloxy or oxogroups, R⁷ represents a hydrogen atom or a methyl group, and R⁸represents a hydrogen atom, a linear or branched alkyl group having 1-6carbon atoms, or a linear or branched alkyl group having 1-6 carbonatoms substituted with one or more alkyloxy, alkylcarbonyloxy or oxogroups.

The polymeric resins of the present invention can further include atleast one additional recurring unit having the formula

wherein where E represents a group derived from non-bridged or bridged,non-substituted or substituted alicyclic hydrocarbons and R⁹ is ahydrogen atom, trifluoromethyl or a methyl group.

The polymeric resins of the invention generally have a molecular weightof between about 2,000 and about 30,000. Additionally, the polymericresins generally have a polydispersity is less than or equal to about1.5. Lastly, the polymeric resins that are prepared by the methods ofthe invention generally include a CTA fragment that can be cleaved bymethods disclosed throughout the specification.

It should be understood that combinations of all monomers (and monomericunits derived from polymers presented herein) are within the scope ofthe invention.

In one aspect of the invention, the polymeric resin is insoluble orscarcely soluble in alkali but becomes alkali soluble by action of anacid. The polymeric resin having the general formula (1), as describedabove, is prepared by LFRP in the presence of a CTA, as describedthroughout the specification. This polymeric resin is hereinafterreferred to as “polymeric resin (A)”.

The term “insoluble or scarcely soluble in alkali” used herein refers tocharacteristics in which 50% or more of the initial film thicknessremains after development in the case of developing a resist filmconsisting only of the resin (A) under alkaline development conditionsemployed when forming a resist pattern using a resist film formed of theradiation-sensitive resin composition comprising the resin (A).

The polymeric resin (A) can include one or more additional recurringmonomeric units described throughout the specification. For example,these recurring units include those noted above as those having formula(3) as described above. The polymeric resin (A) can also includerecurring units having the formula (4) as described above.

As specific examples of the group shown by —C(R²)₃ in the recurring unit(1), a t-butyl group and groups of the following formulas, orsubstituted versions thereof

It should be understood that the above identified —C(R²)₃ groups can bepresent either individually or in combination with one or moreadditional monomers within polymeric resin (A).

Specific example of recurring units having formula (3) include

wherein R⁶ is as defined above.

Alternatively, examples of recurring units having formula (3) include

wherein R⁸ is as defined above.

E in the formula (4) is a group derived from non-bridged or bridgedalicyclic hydrocarbons, and more preferably groups derived fromcyclohexane, norbornane, tricyclodecane, adamantane, or compounds inwhich these groups have one or more hydrogens replaced by a methylgroup.

Suitable examples of the E structure in the formula (4) includehydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group,1-hydroxy-n-propyl group, 2-hydroxy-n-propyl group, 3-hydroxy-n-propylgroup, 1-hydroxy-n-butyl group, 2-hydroxy-n-butyl group,3-hydroxy-n-butyl group, 4-hydroxy-n-butyl group, 3-hydroxycyclopentylgroup, 4-hydroxycyclohexyl group, 5-hydroxy-2-norbornyl group,8-hydroxy-3-tricyclodecanyl group, 8-hydroxy-3-tetracyclododecanylgroup, 3-hydroxy-1-adamantyl group, 3-oxocyclopentyl group,4-oxocyclohexyl group, 5-oxo-2-norbornyl group, 8-oxo-3-tricyclodecanylgroup, 8-oxo-3-tetracyclododecanyl group, 4-oxo-1-adamantyl group,cyanomethyl group, 2-cyanoethyl group, 3-cyano-n-propyl group,4-cyano-n-butyl group, 3-cyanocyclopentyl group, 4-cyanocyclohexylgroup, 5-cyano-2-norbornyl group, 8-cyano-3-tricyclodecanyl group,8-cyano-3-tetracyclododecanyl group, 3-cyano-1-adamantyl group,2-hydroxy-2,2-di(trifluoromethyl)ethyl group,3-hydroxy-3,3-di(trifluoromethyl)-n-propyl group,4-hydroxy-4,4-di(trifluoromethyl)-n-butyl group,5-[2-hydroxy-2,2-di(trifluoromethyl)ethyl]-2-norbornyl group,8-[2-hydroxy-2,2-di(trifluoromethyl)ethyl]-3-tricyclodecanyl group,8-[2-hydroxy-2,2-di(trifluoromethyl)ethyl]-3-tetracyclododecanyl group,and 3-[2-hydroxy-2,2-di(trifluoromethyl)ethyl]-1-adamantyl group.

Of the above-identified E groups, 5-hydroxy-2-norbornyl group,8-hydroxy-3-tricyclodecanyl group, 3-hydroxy-1-adamantyl group,5-cyano-2-norbornyl group, 8-cyano-3-tricyclodecanyl group,3-cyano-1-adamantyl group,5-[2-hydroxy-2,2-di(trifluoromethyl)ethyl]-2-norbornyl group,8-[2-hydroxy-2,2-di(trifluoromethyl)ethyl]-3-tricyclodecanyl group areof particular interest.

The percentage of recurring unit (1) in resin (A) is from about 10 toabout 80 mol %, more particularly from about 20 to about 70 mol %, andstill more specifically from about 20 to about 60 mol % of the totalcontent of the recurring units. The total percentage of the recurringunit (3) or (4), in the resin (A) is from about 20 to about 80 mol %,more particularly from about 20 to about 60 mol %, and still morespecifically from about 30 to about 60 mol % of the total content of therecurring units. The content of other recurring units describedthroughout the specification that can be incorporated into resin (A) isgenerally about 50 mol % or less, and more particularly 30 mol % or lessof the total content of the recurring units.

The resin (A) can be prepared by LFRP. Polymerization of the unsaturatedmonomers is performed in an appropriate solvent, in the presence of achain transfer agent (CTA), and a radical polymerization initiator suchas a hydroperoxide, dialkyl peroxide, diacyl peroxide, or azo compound,as described throughout the specification.

The polystyrene-reduced weight average molecular weight (hereinafterreferred to as “Mw”) of the resin (A) determined by gel permeationchromatography (GPC) is generally from about 1,000 to about 100,000,more particularly from about 1,000 to about 50,000, and still morespecifically from about 2,000-30,000 and still more specifically fromabout 4,000 to about 12,000.

The ratio of Mw to the polystyrene-reduced number average molecularweight (hereinafter referred to as “Mn”) determined by gel permeationchromatography (GPC) (Mw/Mn) of the polymeric resin (A) is generallyfrom about 1 to about 1.8, and more particularly from about 1 to about1.5, e.g., about 1.6.

It is preferable that the resin (A) contains almost no impurities suchas halogens or metals. The smaller the amount of such impurities, thebetter the sensitivity, resolution, process stability, pattern shape,and the like of the polymeric resin when utilized in a coating such as,for example, in a photoresist. The resin (A) can be purified by using achemical purification process, such as reprecipitation, washing withwater, liquid-liquid extraction, or a combination of a chemicalpurification process and a physical purification process such asultrafiltration or centrifugation.

The present invention is also based, at least in part, on the discoverythat photosensitive compositions for use at wavelengths below 248 nm,i.e., 193 nm or 157 nm, can be formulated by combining a photo-acidgenerator and an acrylic or methacrylic based polymeric resin of theinvention that includes ester groups that are sterically bulky. In oneaspect, the ester moiety is a monocyclic, bicyclic, tricyclic, ortetracyclic non-aromatic ring, having 5 or more carbon atoms, and canfurther include a lactone within the cyclic structure. Generation ofacid by photolysis in a photoresist composition induces cleavage of theester group in the polymer resin. This results in a polymeric carboxylicacid that can be removed by treatment with base.

Suitable sterically bulky ester groups include those describedthroughout the specifiction and include, for example, cyclopentanes,cyclohexanes, adamantanes and norbornanes. Examples of monomers used forpreparing the polymeric resins of the invention having the formula[A]_(x)[B]_(y)[C]_(z) include

The monomers useful in the synthesis of the polymeric resins of theinvention can be produced, for example, by reacting correspondinghydroxyl adamantans or norbornanes with either methacrylic or acrylicacid derivatives, such as acyl chloride or acetic anhydrides.

Typically, two or more of the above-identified monomers are polymerizedin either a batch process, continuous or a semi-continuous feed process.

The polymer resins of the invention have the formula[A]_(x)[B]_(y)[C]_(z)  (I)

wherein A, B and C are each individually one of monomers describedthroughout the specification.

In one aspect of the invention, “x” is between about 0 to about 200inclusive, “y” is between about 1 to about 200 inclusive and “z” isbetween about 1 to about 200 inclusive. In another aspect, “x”, “y” and“z” are in the ranges of from about 5 to about 90, from about 10 toabout 75, and from about 25 to about 50. In certain aspects of thepolymeric resins of the invention, x has a value of at least 1.

In another aspect of the invention, “y” and “z” are zero and “x” is anon-zero integer, generally having a value of greater than about 10,therefore providing a homopolymer of the monomers identified throughoutthe application. In certain aspects, the homopolymers are prepared bythe method(s) of the invention. In other aspects, the homopolymers donot include homopolymers of N1 or N2. As discussed throughout thespecification, the homopolymers have a weight average molecular weightof between about 2,000 and about 30,000. Therefore, “x” is between about10 and about 150. Such homopolymers of the invention have apolydispersity of less than about 2, more particularly less than about1.7 and even more particularly between about 1.1 and about 1.4.

In yet another aspect of the invention “x” is at least one and x+y+zequal a total of at least 10. In another aspect, “x”, “y” and “z” eachindividually are in the ranges of from about 5 to about 90, from about10 to about 75, and from about 25 to about 50. In general, x+y+z equalsat least about 10, more particularly at least about 20, and morespecifically at least about 25.

In general, the polymer resins of the invention generally have a weightaverage molecular weight (M_(w)) of between about 2,000 and about30,000. In certain aspects of the invention, the molecular weights ofthe polymeric resins are between about 2,000 and about 20,000, betweenabout 3,000 and about 12,000 and also between about 3,000 and about8,000.

Another important feature of the novel polymers encompassed by thepresent invention is their narrow polydispersity. The terms“polydispersity” and “polydispersity index” (PDI) are recognized in theart and refer to the ratio of the weight average molecular weight to thenumber average molecular weight. Polymeric resins of the inventiontypically have PDI values below about 2, generally less than about 1.7and in particular are between about 1.2 to about 1.4. In some instances,the PDI value is between about 1.1 to about 1.2 or less.

In one embodiment, A, B and C, each individually, are selected from

and x is at least one (1). In a specific embodiment, A, B and C are eachdifferent (A≠B≠C). In one aspect, the ratio of monomers A, B and C areformulated as 50, 35 and 15, respectively, based on weight percent. Morespecifically, an exemplary polymeric resin utilizes each of the threedifferent methacrylic monomers (A, B and C) listed supra and has theformula

(II). Again, it should be understood by one skilled in the art, that inthe polymeric formula [A]_(x)[B]_(y)[C]_(z), monomeric subunits of A, Band C have been polymerized through their respective unsaturatedolefinic portions into a resultant polymeric resin. Polymer resinspertaining to formula (II) generally have a M_(w) of between about 3,000and 12,000 and a PDI of between about 1.1 and about 1.2.

In another aspect, A, B and C, are each individually selected from

where x is at least one (1). In a specific embodiment, A, B and C areeach different (A≠B≠C). In one aspect, the ratio of monomers A, B and Care formulated as 55, 35 and 10, respectively, based on weight percent.For example, a polymer prepared from the three different acrylicmonomers (A, B and C) supra can be represented as a polymeric resinhaving the formula

(III). Polymer resins pertaining to formula (III) generally have a M_(w)of between about 3,000 and 10,000 and a PDI of about 1.3.

In still another embodiment, A, B and C, each individually, are selectedfrom

where x is at least one (1). In a specific embodiment, A, B and C areeach different (A≠B≠C). In one aspect, the ratio of monomers A, B and Care formulated as 55, 35 and 10, respectively, based on weight percent.For example, a polymer prepared from an acrylic monomer and methacrylicmonomers (A, B and C) can be represented by the polymeric resin as

Therefore, acrylic esters, methacrylic esters, and mixtures thereofhaving sterically bulky ester groups have been polymerized by themethods of the invention and are encompassed by the present inventionand are useful, for example, in coatings applications, e.g., photoresistmaterials.

The present invention provides photosensitive polymeric resins of thechemical amplification type. The polymeric resins are suitable for usein photoresist systems where eximer laser lithography is utilized, suchas ArF laser lithography, KrF laser lithography and the like. Thepolymeric resins of the invention provide excellent properties such asresolution, profile, sensitivity, dry etch resistance, adhesion and thelike when used in photoresists.

Polymerization of the monomers (e.g., A, B and C) can be conductedaccording to conventional methods such as bulk polymerization or bysemi-continuous polymerization. For example, the polymeric resin (I) canbe obtained by dissolving requisite monomers in an organic solvent, thenconducting a polymerization reaction in the presence of a polymerizationinitiator, such as an azo compound. Use of a chain transfer agent (CTA)during the polymerization process can be advantageous.

Organic solvents suitable for polymerization reactions of the inventioninclude, for example, ketones, ethers, polar aprotic solvents, esters,aromatic solvents and aliphatic hydrocarbons, both linear and cyclic.Exemplary ketones include methyl ethyl ketone (2-butanone) (MEK),acetone and the like. Exemplary ethers include alkoxyalkyl ethers, suchas methoxy methyl ether or ethyl ether, tetrahydrofuran, 1,4 dioxane andthe like. Polar aprotic solvents include dimethyl formamide, dimethylsulfoxide and the like. Suitable esters include alkyl acetates, such asethyl acetate, methyl acetate and the like. Aromatic solvents includealkylaryl solvents, such as toluene, xylene and the like and halogenatedaromatics such as chlorobenzene and the like. Hydrocarbon type solventsinclude, for example, hexane, cyclohexane and the like.

The polymerization conditions that can be used include temperatures forpolymerization typically in the range of from about 20° C. to about 110°C., more specifically in the range of from about 50° C. to about 90° C.and even more specifically in the range of from about 60° C. to about80° C. The atmosphere can be controlled, with an inert atmosphere beingadvantageous, such as nitrogen or argon. The molecular weight of thepolymer is controlled via adjusting the ratio of monomer to CTA.Generally, the molar ratio of monomer to CTA is in the range of fromabout 5:1 to about 200:1, more specifically in the range of from about10:1 to about 100:1, and most particularly from 10:1 to about 50:1.

A free radical source is provided in the polymerization mixture, whichcan stem from spontaneous free radical generation upon heating or in oneaspect, from a free radical initiator (radical source generator). In thelatter case the initiator is added to the polymerization mixture at aconcentration high enough for an acceptable polymerization rate (e.g.,commercially significant conversion in a certain period of time, such aslisted below). Conversely, a too high free radical initiator to CTAratio will favor unwanted dead polymer formation through radical-radicalcoupling reaction leading to polymer materials with uncontrolledcharacteristics. The molar ratio of free radical initiator to CTA forpolymerization are typically in the range of from about 0.5:1 to about0.02:1, e.g., 0.2:1.

The phrase “free-radical source,” within the context of the invention,refers broadly to any and all compounds or mixtures of compounds thatcan lead to the formation of radical species under appropriate workingconditions (thermal activation, irradiation, redox conditions, etc.).

Polymerization conditions also include the time for reaction, which canbe from about 0.5 hours to about 72 hours, and more particularly in therange of from about 1 hour to about 24 hours, and even more particularlyin the range of from about 2 hours to about 12 hours. Conversion ofmonomer to polymer is at least about 50%, more particularly at leastabout 75% and even more particularly at least about 90% or greater.

The initiators employed in the present invention can be a commerciallyavailable free-radical initiator. In general, however, initiators havinga short half-life at the polymerization temperature are utilized inparticular. Such initiators are utilized because the speed of theinitiation process can affect the polydispersity index of the resultingpolymer. That is, the kinetics of controlled, living polymerization aresuch that less polydisperse polymer samples are prepared if initiationof all chains occurs at substantially the same time. More specifically,suitable free radical initiators include any thermal, redox or photoinitiators, including, for example, alkyl peroxides, substituted alkylperoxides, aryl peroxides, substituted aryl peroxides, acyl peroxides,alkyl hydroperoxides, substituted alkyl hydroperoxides, arylhydroperoxides, substituted aryl hydroperoxides, heteroalkyl peroxides,substituted heteroalkyl peroxides, heteroalkyl hydroperoxides,substituted heteroalkyl hydroperoxides, heteroaryl peroxides,substituted heteroaryl peroxides, heteroaryl hydroperoxides, substitutedheteroaryl hydroperoxides, alkyl peresters, substituted alkyl peresters,aryl peresters, substituted aryl peresters, azo compounds and halidecompounds. Specific initiators include cumene hydroperoxide (CHP),t-butyl hydroperoxide (TBHP), t-butyl perbenzoate (TBPB), sodiumcarbonateperoxide, benzoyl peroxide (BPO), lauroyl peroxide (LPO),methylethylketone peroxide 45%, potasium persulfate, ammoniumpersulfate, 2,2-azobis(2,4-dimethyl-valeronitrile) (VAZO®-65),1,1-azobis(cyclo-hexanecarbonitrile) (VAZO®-40),2,2-azobis(N,N′-dimethyleneisobutyramidine)dihydrochloride (VAZO®-044),2,2-azobis(2-amidino-propane)dihydrochloride (VAZO®-50) and2,2-azobis(2-amido-propane) dihydrochloride. Redox pairs such aspersulfate/sulfite and Fe(2⁺)/peroxide are also useful. Initiation mayalso be by heat or UV light, as is known in the art, depending on theembodiment being practiced (e.g., UV light may be used for the modifiedinitiator or RAFT or MADIX techniques discussed herein). Those of skillin the art can select a proper initiator within the scope of thisinvention.

Chain transfer agents (CTAs) are known in the art and are used to helpcontrol free radical polymerizations. Ultimately, many different typesof CTAs can be incorporated into the terminus of a polymer as furtherexplained below. Examples of suitable CTAs useful in the presentinvention include those described in U.S. Pat. No. 6,512,021,WO98/01478, WO99/35177, WO99/31144, WO99/05099 and WO98/58974, each ofwhich is incorporated herein by reference.

Additional examples include CTAs described in U.S. Pat. Nos. 6,395,850,6,518,364, U.S. patent application Ser. No. 10/407,405, entitled“Cleaving and Replacing Thio Control Agent Moieties from Polymers madeby Living-Type Free Radical Polymerization” filed on Apr. 3, 2003 andU.S. patent application Ser. No. 10/104,740, filed Mar. 22, 2002, theteachings of which are incorporated herein by reference in theirentirety.

The use and mechanism of reversible control agents for free radicalpolymerization is now generally known and coined as RAFT (ReversibleAddition Fragmentation Transfer), see for example, U.S. Pat. No.6,153,705, WO 98/01478, WO 99/35177, WO 99/31144, and WO 98/58974, eachof which is incorporated herein by reference. Recently new agents havebeen disclosed which are readily available for polymerizing desiredmonomers under commercially acceptable conditions, which include highconversion at the shortest possible reaction times and lowertemperatures, see for example U.S. Pat. Nos. 6,380,335, 6,395,850, and6,518,364, each of which is incorporated herein by reference.

In general CTAs useful in the present invention have the generalformula:

wherein R^(x) is generally any group that is sufficiently labile to beexpelled as its free radical form, T is carbon or phosphorus, and Z isany group that activates the C═S double bond towards a reversible freeradical addition fragmentation reaction and may be selected from thegroup consisting of amino and alkoxy. In other embodiments, Z isattached to C═S through a carbon atom (dithioesters), a nitrogen atom(dithiocarbamate), a sulfur atom (trithiocarbonate) or an oxygen atom(dithiocarbonate). Specific examples for Z can be found in WO98/01478,WO99/35177, WO99/31144, and WO98/58974, each of which is incorporatedherein by reference. In some embodiments, Z is selected from the groupconsisting of hydrocarbyl, substituted hydrocarbyl,heteroatom-containing hydrocarbyl, substituted heteroatom-containinghydrocarbyl, and combinations thereof. More specifically, Z may beselected from the group consisting of hydrogen, optionally substitutedalkyl, optionally substituted aryl, optionally substituted alkenyl,optionally substituted acyl, optionally substituted, aroyl, optionallysubstituted alkoxy, optionally substituted heteroaryl, optionallysubstituted heterocyclyl, optionally substituted alkylsulfonyl,optionally substituted alkylsulfinyl, optionally substitutedalkylphosphonyl, optionally substituted arylsulfinyl, and optionallysubstituted arylphosphonyl.

In particular, suitable CTAs useful in the present invention includethose identified in U.S. Pat. No. 6,380,335, the contents of which areincorporated by reference. More specifically, CTAs of particularinterest in combination with the monomers utilized throughout thespecification can be characterized by the general formula:

wherein D is S, Te or Se. In one aspect, D is sulfur. R¹ is generallyany group that can be easily expelled under its free radical form (R¹.)upon an addition-fragmentation reaction, as depicted below in Scheme A(showing D as S):

In Scheme A, P. is a free radical, typically a macro-radical, such aspolymer chain. More specifically, R¹ is selected from the groupconsisting of hydrocarbyl, substituted hydrocarbyl,heteroatom-containing hydrocarbyl, and substituted heteroatom-containinghydrocarbyl, and combinations thereof. Even more specifically, R¹ isselected from the group consisting of optionally substituted alkyl,optionally substituted aryl, optionally substituted alkenyl, optionallysubstituted alkoxy, optionally substituted heterocyclyl, optionallysubstituted alkylthio, optionally substituted amino and optionallysubstituted polymer chains. And still more specifically, R¹ is selectedfrom the group consisting of —CH₂Ph, —CH(CH₃)CO₂CH₂CH₃, —CH(CO₂CH₂CH₃)₂,—C(CH₃)₂CN, —CH(Ph)CN, —C(CH₃)₂CO₂R (alkyl, aryl, etc.) and —C(CH₃)₂Ph.

Also, R² and R³ of the CTA are each independently selected from thegroup consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl,heteroatom-containing hydrocarbyl, and substituted heteroatom-containinghydrocarbyl, and combinations thereof. More specifically, R² and R³ canbe each independently selected from the group consisting of hydrogen,optionally substituted alkyl, optionally substituted aryl, optionallysubstituted alkenyl, optionally substituted acyl, optionallysubstituted, aroyl, optionally substituted alkoxy, optionallysubstituted heteroaryl, optionally substituted heterocyclyl, optionallysubstituted alkylsulfonyl, optionally substituted alkylsulfinyl,optionally substituted alkylphosphonyl, optionally substitutedarylsulfinyl, and optionally substituted arylphosphonyl. Specificembodiments of R² and/or R³ are listed in the above definitions, and inaddition include perfluorenated aromatic rings, such as perfluorophenyl.Also optionally, R² and R³ can together form a double bond alkenylmoiety off the nitrogen atom, and in that case R² and R³ are togetheroptionally substituted alkenyl moieties.

Finally, R⁴ of the CTA is selected from the group consisting ofhydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containinghydrocarbyl, and substituted heteroatom-containing hydrocarbyl, andcombinations thereof; and optionally, R⁴ combines with R² and/or R³ toform a ring structure, with said ring having from 3 to 50 non-hydrogenatoms. In particular, R⁴ is selected from the group consisting ofhydrogen, optionally substituted alkyl, optionally substituted aryl,optionally substituted alkenyl, optionally substituted acyl, optionallysubstituted aryl, amino, thio, optionally substituted aryloxy andoptionally substituted alkoxy. Specific R⁴ groups include methyl andphenyl.

As used herein, the phrase “having the structure” is not intended to belimiting and is used in the same way that the term “comprising” iscommonly used. The term “independently selected from the groupconsisting of” is used herein to indicate that the recited elements,e.g., R groups or the like, can be identical or different (e.g., R² andR³ in the structure of formula (1) may all be substituted alkyl groups,or R² may be hydrido and R³ may be methyl, etc.).

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where said event or circumstance occurs and instances where itdoes not. For example, the phrase “optionally substituted hydrocarbyl”means that a hydrocarbyl moiety may or may not be substituted and thatthe description includes both unsubstituted hydrocarbyl and hydrocarbylwhere there is substitution.

The term “alkyl” as used herein refers to a branched or unbranchedsaturated hydrocarbon group typically although not necessarilycontaining 1 to about 24 carbon atoms, such as methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl, and the like, aswell as cycloalkyl groups such as cyclopentyl, cyclohexyl and the like.Generally, although again not necessarily, alkyl groups herein contain 1to about 12 carbon atoms. The term “lower alkyl” intends an alkyl groupof one to six carbon atoms, preferably one to four carbon atoms.“Substituted alkyl” refers to alkyl substituted with one or moresubstituent groups, and the terms “heteroatom-containing alkyl” and“heteroalkyl” refer to alkyl in which at least one carbon atom isreplaced with a heteroatom.

The term “alkenyl” as used herein refers to a branched or unbranchedhydrocarbon group typically although not necessarily containing 2 toabout 24 carbon atoms and at least one double bond, such as ethenyl,n-propenyl, isopropenyl, n-butenyl, isobutenyl, octenyl, decenyl, andthe like. Generally, although again not necessarily, alkenyl groupsherein contain 2 to about 12 carbon atoms. The term “lower alkenyl”intends an alkenyl group of two to six carbon atoms, preferably two tofour carbon atoms. “Substituted alkenyl” refers to alkenyl substitutedwith one or more substituent groups, and the terms“heteroatom-containing alkenyl” and “heteroalkenyl” refer to alkenyl inwhich at least one carbon atom is replaced with a heteroatom.

The term “alkynyl” as used herein refers to a branched or unbranchedhydrocarbon group typically although not necessarily containing 2 toabout 24 carbon atoms and at least one triple bond, such as ethynyl,n-propynyl, isopropynyl, n-butynyl, isobutynyl, octynyl, decynyl, andthe like. Generally, although again not necessarily, alkynyl groupsherein contain 2 to about 12 carbon atoms. The term “lower alkynyl”intends an alkynyl group of two to six carbon atoms, preferably three orfour carbon atoms. “Substituted alkynyl” refers to alkynyl substitutedwith one or more substituent groups, and the terms“heteroatom-containing alkynyl” and “heteroalkynyl” refer to alkynyl inwhich at least one carbon atom is replaced with a heteroatom.

The term “alkoxy” as used herein intends an alkyl group bound through asingle, terminal ether linkage; that is, an “alkoxy” group may berepresented as —O-alkyl where alkyl is as defined above. A “loweralkoxy” group intends an alkoxy group containing one to six, morepreferably one to four, carbon atoms. The term “aryloxy” is used in asimilar fashion, with aryl as defined below.

Similarly, the term “alkyl thio” as used herein intends an alkyl groupbound through a single, terminal thioether linkage; that is, an “alkylthio” group may be represented as —S-alkyl where alkyl is as definedabove. A “lower alkyl thio” group intends an alkyl thio group containingone to six, more preferably one to four, carbon atoms.

The term “allenyl” is used herein in the conventional sense to refer toa molecular segment having the structure —CH═C═CH2. An “allenyl” groupmay be unsubstituted or substituted with one or more non-hydrogensubstituents.

The term “aryl” as used herein, and unless otherwise specified, refersto an aromatic substituent containing a single aromatic ring or multiplearomatic rings that are fused together, linked covalently, or linked toa common group such as a methylene or ethylene moiety. The commonlinking group may also be a carbonyl as in benzophenone, an oxygen atomas in diphenylether, or a nitrogen atom as in diphenylamine. Preferredaryl groups contain one aromatic ring or two fused or linked aromaticrings, e.g., phenyl, naphthyl, biphenyl, diphenylether, diphenylamine,benzophenone, and the like. In particular embodiments, aryl substituentshave 1 to about 200 carbon atoms, typically 1 to about 50 carbon atoms,and preferably 1 to about 20 carbon atoms. “Substituted aryl” refers toan aryl moiety substituted with one or more substituent groups, (e.g.,tolyl, mesityl and perfluorophenyl) and the terms “heteroatom-containingaryl” and “heteroaryl” refer to aryl in which at least one carbon atomis replaced with a heteroatom.

The term “aralkyl” refers to an alkyl group with an aryl substituent,and the term “aralkylene” refers to an alkylene group with an arylsubstituent; the term “alkaryl” refers to an aryl group that has analkyl substituent, and the term “alkarylene” refers to an arylene groupwith an alkyl substituent.

The terms “halo” and “halogen” are used in the conventional sense torefer to a chloro, bromo, fluoro or iodo substituent. The terms“haloalkyl,” “haloalkenyl” or “haloalkynyl” (or “halogenated alkyl,”“halogenated alkenyl,” or “halogenated alkynyl”) refers to an alkyl,alkenyl or alkynyl group, respectively, in which at least one of thehydrogen atoms in the group has been replaced with a halogen atom.

The term “heteroatom-containing” as in a “heteroatom-containinghydrocarbyl group” refers to a molecule or molecular fragment in whichone or more carbon atoms is replaced with an atom other than carbon,e.g., nitrogen, oxygen, sulfur, phosphorus or silicon. Similarly, theterm “heteroalkyl” refers to an alkyl substituent that isheteroatom-containing, the term “heterocyclic” refers to a cyclicsubstituent that is heteroatom-containing, the term “heteroaryl” refersto an aryl substituent that is heteroatom-containing, and the like. Whenthe term “heteroatom-containing” appears prior to a list of possibleheteroatom-containing groups, it is intended that the term apply toevery member of that group. That is, the phrase “heteroatom-containingalkyl, alkenyl and alkynyl” is to be interpreted as“heteroatom-containing alkyl, heteroatom-containing alkenyl andheteroatom-containing alkynyl.”

“Hydrocarbyl” refers to univalent hydrocarbyl radicals containing 1 toabout 30 carbon atoms, preferably 1 to about 24 carbon atoms, mostpreferably 1 to about 12 carbon atoms, including branched or unbranched,saturated or unsaturated species, such as alkyl groups, alkenyl groups,aryl groups, and the like. The term “lower hydrocarbyl” intends ahydrocarbyl group of one to six carbon atoms, preferably one to fourcarbon atoms. “Substituted hydrocarbyl” refers to hydrocarbylsubstituted with one or more substituent groups, and the terms“heteroatom-containing hydrocarbyl” and “heterohydrocarbyl” refer tohydrocarbyl in which at least one carbon atom is replaced with aheteroatom.

By “substituted” as in “substituted hydrocarbyl,” “substituted aryl,”“substituted alkyl,” “substituted alkenyl” and the like, as alluded toin some of the aforementioned definitions, is meant that in thehydrocarbyl, hydrocarbylene, alkyl, alkenyl or other moiety, at leastone hydrogen atom bound to a carbon atom is replaced with one or moresubstituents that are groups such as hydroxyl, alkoxy, thio, phosphino,amino, halo, silyl, and the like. When the term “substituted” appearsprior to a list of possible substituted groups, it is intended that theterm apply to every member of that group. That is, the phrase“substituted alkyl, alkenyl and alkynyl” is to be interpreted as“substituted alkyl, substituted alkenyl and substituted alkynyl.”Similarly, “optionally substituted alkyl, alkenyl and alkynyl” is to beinterpreted as “optionally substituted alkyl, optionally substitutedalkenyl and optionally substituted alkynyl.”

As used herein the term “silyl” refers to the —SiZ1Z2Z3 radical, whereeach of Z1, Z2, and Z3 is independently selected from the groupconsisting of hydrido and optionally substituted alkyl, alkenyl,alkynyl, aryl, aralkyl, alkaryl, heterocyclic, alkoxy, aryloxy andamino.

As used herein, the term “phosphino” refers to the group —PZ1Z2, whereeach of Z1 and Z2 is independently selected from the group consisting ofhydrido and optionally substituted alkyl, alkenyl, alkynyl, aryl,aralkyl, alkaryl, heterocyclic and amino.

The term “amino” is used herein to refer to the group —NZ1Z2, where eachof Z1 and Z2 is independently selected from the group consisting ofhydrido and optionally substituted alkyl, alkenyl, alkynyl, aryl,aralkyl, alkaryl and heterocyclic.

The term “thio” is used herein to refer to the group —SZ1, where Z1 isselected from the group consisting of hydrido and optionally substitutedalkyl, alkenyl, alkynyl, aryl, aralkyl, alkaryl and heterocyclic.

As used herein all reference to the elements and groups of the PeriodicTable of the Elements is to the version of the table published by theHandbook of Chemistry and Physics, CRC Press, 1995, which sets forth thenew IUPAC system for numbering groups.

In certain embodiments, R⁴ combines with either R² or R³ to form asubstituted or unsubstituted pyrazole moiety.

Exemplary CTAs include, for example,

In some embodiments, the resulting polymers of the invention describedabove will have one or more termini having, for example, a thio group(from a CTA). Depending on the application intended for the polymer, thethio group may be undesirable. Thus, this invention also providespolymeric resins that have the CTA eliminated from the polymeric resintermini.

In certain embodiments described throughout the specification, theresulting polymer contains a CTA moiety (a portion of the CTA, such asthe dithio carbonyl portion) at a terminal end, whether the end is atthe end of a backbone, a star arm, a comb end, a branch end, or a graft.Removal of the CTA can be accomplished by several methods describedbelow. Mechanistically, a free radical chain transfer reaction isbelieved to decouple a residue, such as the dithio CTA moiety, from thepolymer end by addition of an external radical source.

In one embodiment, it is advantageous in some instances to remove atleast the sulfur containing portion of the CTA from the polymer terminalend (if present) position by cleaving the CTA moiety (e.g., athiocarbonylthio moiety, a thio group) from the polymer terminus. In oneembodiment, this can be accomplished by radical reduction of thedithiocarbonyl or dithiophosphoryl groups using a free radicalintitiator and a compound bearing a labile hydrogen atom. The methodessentially removes the unwanted group from the polymer chain end andreplaces it with a hydrogen atom. See for example, WO 02/090397, whichis incorporated herein by reference in its entirety.

In another aspect, the CTA can be replaced by use of excess initiator,whereby a fragmentation product of the initiator replaces the CTA at thetermini of the polymer as described in U.S. patent application Ser. No.10/407,405, entitled “Cleaving and Replacing Thio Control Agent Moietiesfrom Polymers made by Living-Type Free Radical Polymerization” filed onApr. 3, 2003, the teachings of which are incorporated herein byreference in their entirety.

In yet another aspect, the CTA can be replaced by use of initiator incombination with a RAFT agent as described in U.S. patent applicationSer. No. 10/407,405, entitled “Cleaving and Replacing Thio Control AgentMoieties from Polymers made by Living-Type Free Radical Polymerization”filed on Apr. 3, 2003, the teachings of which are incorporated herein byreference in their entirety.

In still another aspect, the CTA can be replaced by anon-homopolymerizable monomer that is introduced with the radical sourceas described in U.S. patent application Ser. No. 10/609,255, entitled“Removal of the Thiocarbonylthio or Thiophosphorylthio End Group ofPolymers and Further Functionalization Thereof” filed on Jun. 26, 2003,the teachings of which is incorporated herein by reference in theirentirety.

Wishing not to be bound to any particular theory, it is thought thecleavage of the thio group from the polymer proceeds through a set ofreactions described below in Schemes 1 and 2:

where P represents the polymer, T is carbon or phosphorus, S is sulfur,I₂ a free radical source, I. is a free radical stemming from I₂decomposition, and Z is as defined above. Scheme 1 represents theactivation of the free radical initiator yielding radical I.; and scheme2 represents the addition-fragmentation of I. on the dithio-terminatedpolymer generating a polymer radical P..

In some embodiments, the external radical source is a common radicalinitiator, such as any initiator listed above. Regardless of its exactnature, the free-radical source implemented in the procedure accordingto the invention is utilized under cleavage reaction conditions thatallow for the production of free radicals, which, in one embodiment, isaccomplished via thermal activation, i.e., by raising the temperature ofthe reaction medium, usually to a temperature in the range of about roomtemperature (approximately 20° C.) to about 200° C., and specificallyfrom about 40° C. to about 180° C., and more specifically from about 50°C. to about 120° C. In other embodiments, free radicals are produced vialight activation. This includes free radical sources activatable by UVlight, such as benzoin ethers, and benzophenone. High energy radiationssuch as Gamma rays and electron beams are also known to produceradicals.

The free-radical source utilized can be introduced into the reactionmedium in one single increment. However, it can also be introducedgradually, either by portions or continuously.

The cleavage reaction conditions that can be used include conditionssuch as temperature, pressure, atmosphere, reaction times and ratios ofreaction components. Temperatures useful are those in the range of fromabout room temperature (approximately 20° C.) to about 200° C., andspecifically from about 40° C. to about 180° C., and more specificallyfrom about 50° C. to about 120° C. In some embodiments, the atmospherecan be controlled, with an inert atmosphere being utilized, such asnitrogen or argon. In other embodiments, ambient atmosphere is used. Thecleavage reaction conditions also include open or closed atmospheres andpressures at ambient conditions. In embodiments in which the cleavagereaction is carried out in a closed atmosphere, and the temperature isabove room temperature, the pressure could rise as a result of anyheated solvents. In some embodiments light control is also desired.Specifically, the reaction can be carried out in visible light, or underUV light.

The quantity of the free-radical source depends on its effectiveness, onthe manner in which the source is introduced, and on the desired endproduct. The free-radical source that is utilized can be introduced in aquantity such that the amount of free radicals that can be released bythe source is between about 1% and about 800% (molar), specificallybetween about 50% and about 400% (molar), and more specifically betweenabout 100% and about 300% (molar), and more specifically between about200% and about 300% in relation to the total molar amount of the groupsin the polymers for which cleavage is desired. In some embodiments,complete removal or as near as complete as possible is desired and inthose embodiments, an excess of free radical source is introduced.

The excess free radical source is intended to account for the sidereactions that are well known in free radical processes such as thosementioned below (e.g. scheme 5), as well as the possible free radicalloss caused by the cage effect. When available, the free radical sourceefficiency factor, f, defined as the ratio of active radicals to totalradicals generated upon free radical source decomposition, can be usedto adjust the concentration of I₂.

Most known free radical sources can be used, as long as the half-lifetime (defined as the time after which half of the free radical sourcehas been consumed) is between approximately 10 minutes and 20 hours.

Typical initiators that can be used as a free radical source areselected among alkyl peroxides, substituted alkyl peroxides, arylperoxides, substituted aryl peroxides, acyl peroxides, alkylhydroperoxides, substituted alkyl hydroperoxides, aryl hydroperoxides,substituted aryl hydroperoxides, heteroalkyl peroxides, substitutedheteroalkyl peroxides, heteroalkyl hydroperoxides, substitutedheteroalkyl hydroperoxides, heteroaryl peroxides, substituted heteroarylperoxides, heteroaryl hydroperoxides, substituted heteroarylhydroperoxides, alkyl peresters, substituted alkyl peresters, arylperesters, substituted aryl peresters, dialkylperdicarbonate, inorganicperoxides, hyponitrites and azo compounds. Specific initiators includelauroyl and benzoylperoxide (BPO) and AIBN. Some azo compounds include1,1′-Azobis(cyclohexane-1-carbonitrile),2,2′-Azobis(4-methoxy-2,4-dimethyl valeronitrile), Dimethyl2,2′-azobis(2-methylpropionate), 1-[(cyano-1-methylethyl)azo]formamide,2,2′-Azobis(N-cyclohexyl-2-methylpropionamide), 2,2′-Azobis(2,4-dimethylvaleronitrile), 2,2′-Azobis(2-methylbutyronitrile),2,2′-Azobis[N-(2-propenyl)-2-methylpropionamide],2,2′-Azobis(N-butyl-2-methylpropionamide),2,2′-Azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride,2,2′-Azobis[2-(2-imidazolin-2-yl)propane disulfate dihydrate,2,2′-Azobis[N-(2-carboxyethyl)-2-methylpropionamidine]tetrahydrate,2,2′-Azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane}dihydrochloride,2,2′-Azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide, 2,2′-Azobis[2-methyl-N-(2-hydroxyethyl)propionamide],2,2′-Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride,2,2′-Azobis(2-methylpropionamide)dihydrochloride,2,2′-Azobis[2-(3,4,5,6-tetrahydropyrimidin-2-yl)propane]dihydrochloride, 2,2′-Azobis[2-(2-imidazolin-2-yl)propane], and2,2′-Azobis{2-methyl-N-[2-(1-hydroxybuthyl)]propionamide}. This includesinitiators activatable by UV such as benzoin ethers, and benzophenone.Other initiators are activatable by high energy such as gamma rays andelectron beams. The half-life time can be adjusted by setting thereaction temperature to the required range. The latter is determined bythe temperature dependence of the initiator decomposition rate,available through the supplier information package or in the literature(e.g. “The Chemistry of Free Radical Polymerization, G. Moad, D. H.Salomon, Eds. Pergamon Pub. 1995). The rate of decomposition, hence theradical production, is also adjustable by the addition of reducingagents, in particular when the initiator has an oxidizing character,such as peroxides: for instance metabisulfite, ascorbic acid,sulfite-formaldehyde adduct, amines, and low oxidation state metals,etc., can be used together with peroxides type initiators to acceleratethe radical flux.

Cleavage reaction conditions also include the time for reaction, whichcan be from about 0.5 hours to about 72 hours, more particularly in therange of from about 1 hour to about 24 hours, and even more particularlyin the range of from about 2 hours to about 12 hours. Cleavage of thiogroup, for example, from the polymer is at least about 50%, morespecifically at least about 75% and more specifically at least about85%, and even more specifically at least about 95%. Replacement of thethio groups is at least about 50%, more specifically at least about 75%and more specifically at least about 85%, and even more specifically atleast about 95%.

The thio groups can be replaced with a variety of different moieties asdetailed above with various RAFT agents, etc. In one embodiment, asdescribed in WO 02/090397 (assigned to Rhodia Chimie), the thio moietyof the CTA can be replaced by a hydrogen atom. In another embodiment,the thio group can be replaced by a non homopolymerizable monomer unit.In still another embodiment, only a free radical source is introduced tocap the polymer termini.

The cleavage reaction mixture can use a reaction media that is typicallya solvent. Cleavage reaction conditions also include stirring orrefluxing the reaction media. The resulting polymer radical, P., canthen be capped in one of three ways as shown below in Schemes 3, 4 and5:

Scheme 3 represents the radical coupling of the polymer radicalgenerated in scheme 2 and the free radical generated in scheme 1, whichproduces the resulting capped polymer P—I. Scheme 4 represents atransfer reaction between the polymer radical generated in scheme 2 andthe free radical initiator that produces the cleaved polymer as well anew free radical source. Scheme 5 represents a coupling reaction betweentwo polymer radicals.

In one embodiment, schemes 3 and 4 are the desired reactions. Scheme 5is a side reaction that contributes in increasing molecular weight andbroadening molecular weight distribution of the bulk polymer sample. Ithas been found that the described cleavage reaction conditions lead toquantitative cleavage of dithiocompounds, for example, with little to nochange in molecular weight characteristics (Mw and polydispersityindex).

In one embodiment, the polymer is treated with free radical source, suchas an initiator, under cleavage reaction conditions so that thereactions 3 and 4 are favored. These conditions include introducing theradical source in a quantity such that the amount of free radicals thatcan be released by the source is between about 200% and about 500%(molar), specifically between about 200% and about 300% (molar) inrelation to the total molar amount of the groups in the polymers forwhich cleavage is desired.

The resulting polymer has a new group at its terminus which may make thepolymer more desirable for specific applications. For example, thepolymer above may be more desirable for applications that cannot allowthe presence of sulfur in the amounts present in the polymer beforemodification, such as home and personal care products where odor maypresent a problem.

It is advantageous that the reaction product, either with a CTA terminalgroup or without, is purified by re-precipitation or the like, aftercompletion of the polymerization reaction. Typical precipitation agentsinclude low molecular weight alcohols, such as isopropyl, methyl, ethyl,and butyl alcohols.

Procedure for the Living Polymerization of Methacrylate and AcrylateMonomers Encompassed by the Invention

The following is a general procedure for use with a CTA. (See Table I,column C) for the polymerization of monomers to form a polymer with thedesired nominal compositions (Table I, column H) and targeted to havedifferent molecular weights (Mw) at 100% conversion. The polymerizationwas conducted in an organic solvent, i.e., MEK (2-butanone) (which wasdegassed by three freeze-pump-thaw cycles) and the initiator MAIB (V601from WAKO, 2,2′-dimethylazobis (methylpropionate)) was used to sustainthe reaction. The stock solutions were made by weighing the monomers,CTA and initiator followed by cycling with vacuum into an oxygen freebox where purified MEK was added.

Similar conditions can be used for other comonomer mixtures and withother CTAs. Target molecular weight is set as a molar ratio of themonomers to the CTA. The feed time can also be varied (Table I, columnG). Feed times effect the target molecular weight, the polymercomposition (due to reactivity ratios and the subsequent monomer drift)as well as the PDI.

For example, reaction conditions for CTA H-AB-1 with acrylates generallyrequire a three hour feed time followed by six hours of continuedheating at 65° C. In contrast, reaction conditions for CTA H-T-3 withmethacrylates generally require six hours feed time followed by twohours of continued heating at 80° C.

Example to Prepare a Polymer with a Nominal CompositionN1/P1/Q1(50/35/15) and Mw Targeted at 6000 g/mol at 100% ConversionUsing CTA-HT3 as Controlling Agent

Stock Solutions (ss) are:

1) “Monomer Mixture”: 17.830 g N1+16.708 g P1+6.315 g Q1+145 mL MEK

2) “MAIB Solution”: 1.271 g MAIB+30 mL MEK

3) “CTA Solution”: 1.417 g CTA-H-T-3+7.044 mL MEK to get 8.804 mL ofstock solution

4) “MEK” (pure): 29.150 mL MEK

Reaction:

1) A 500 mL glass reaction flask equipped with a magnetic stir bar and areflux condenser was cycled into the glove box.

2) All of “CTA Solution” (8.804 mL), and all of the “MEK” were added tothe reaction flask, as well as 1.918 mL of “MAIB Solution” and 19.285 mLof “Monomer Mixture” (10% of each of these solutions).

3) The reaction flask was then removed from the glove box and themixture was degassed by three freeze-pump-thaw cycles, followed bybackfilling of the system with high purity nitrogen or argon (and leftunder a bubbler of inert gas).

4) The “Monomer Mixture” and “MAIB Solution” were then primed on twofeed pumps which were then attached to the reaction flask. (The sealedbottles of the two stock solutions were placed under an inert gasbubbler.)

5) The flask was the submerged into an oil bath at 85° C. and stirringwas set at 400 rpm.

6) Once the reaction mixture reached 85° C., the semicontinuous additionof 173.57 mL of “Monomer Mixture” and 17.27 mL of “MAIB Solution” wasbegun, and added over the next six hours in a series of 100 equal volumeinjections while maintaining an internal temperature of 85° C.

7) Heating of the reaction mixture at 85° C. was continued for anadditional two hours past the end of the feed.

8) The reactor was then cooled to room temperature (approximately 45-50minutes). The reaction mixture was concentrated by removing half of thesolvent (MEK). The mixture was then precipitated slowly into 2 L ofisopropanol, washed with an additional 500 mL of isopropanol, and driedunder vacuum at 45° C. for two days.

9) 35.2 g of dry polymer was isolated with an Mw=6200 g/mol, and aPDI=1.30 (sample 11693911). Other samples were prepared in similarfashion with an isolation of polymer ranging from 0.5 grams to 50 gramsyield after precipitation.

Example to Prepare a Polymer with a Nominal CompositionN2/P5/Q3(55/35/10) and Mw targeted at 15000 g/mol at 100% ConversionUsing CTA-HAB1 as Controlling Agent

Stock Solutions (ss) are:

1) “Monomer Mixture”: 20.95 g N2+18.86 g P5+4.47 g Q3+110 mL MEK

2) “MAIB Solution”: 0.636 g MAIB+15 mL MEK

3) “CTA Solution”: 0.763 g CTA-H-AB-1+3.79 mL MEK

4) “MEK” (pure): 91 mL MEK

Reaction:

5) A 500 mL glass reaction flask equipped with a magnet stir bar and areflux condenser was cycled into the glove box.

6) All of “CTA Solution”, and all of the “MEK” were added to thereaction flask, as well as 0.461 mL of “MAIB Solution” and 15.0 mL of“Monomer Mixture” (10% of each of these solutions).

7) The reaction flask was then removed from the glove box and themixture was degassed by three freeze-pump-thaw cycles, followed bybackfilling of the system with high purity nitrogen or argon (and leftunder a bubbler of inert gas).

8) The “Monomer Mixture” and “MAIB Solution” were then primed on twofeed pumps which were then attached to the reaction flask. (The sealedbottles of the two stock solutions were placed under inert gas bubbler.)

9) The flask was the submerged into an oil bath at 70° C. and stirringwas set at 400 rpm.

10) Once the reaction mixture reached 65° C., the semicontinuousaddition of 135 mL of “Monomer Mixture” and 4.145 mL of “MAIB Solution”was begun, and added over the next three hours in a series of 100 equalvolume injections while maintaining an internal temperature of 65° C.

11) Heating of the reaction mixture at 65° C. was continued for anadditional three hours past the end of the feed.

12) The reactor was then cooled to room temperature (approximately 45-50minutes) and the reaction mixture was precipitated slowly into 2 L ofisopropanol, washed with an additional 500 mL of isopropanol, and driedunder vacuum at 45° C. for two days.

13) 26 g of dry polymer was isolated with an Mw=6900, and a PDI=1.35(sample 11692711 (A4)). Other samples were prepared in similar fashionwith an isolation of polymer ranging from 0.5 grams to 50 grams yieldafter precipitation.

Example to Prepare Polymers with a Nominal CompositionN1/P1/Q1(50/35/15) at Different Molecular Weights Using CTA-HT3 asControlling Agent in a Library Format (116959)

Stock Solutions (ss) were prepared in an inert atmosphere and aretypically:

1) “Monomer Mixture”: 17.215 g N1+16.13 g P1+6.097 g Q1+140 mL MEK

2) “MAIB Solution”: 1.896 g MAIB+50 mL MEK

3) “CTA Solution”: 1.242 g CTA-H-T-3+3.6 mL MEK to get 5.143 mL of stocksolution

4) “MEK” (pure): 29.150 mL MEK

Reaction:

5) All of “CTA Solution” (ss-CTA-HT3) was preliminary equally added to24 individual reactor vessels of a Semi-Continuous Parallel PressurizedReactor (Table 3, “ss-CTA-HTs).

6) Three individuals lines (2, 3 and 4) were respectively primed withsolvent (MEK), ss-MAIB and monomer solution before sealing of thereactor vessels.

7) The reactor vessels were degassed by a pressurization, pressurerelieve and backfilling under inert-cycles with high purity argon.

8) Solutions dispensed in each of the 24 reactor vessels were mentionedin Table 3 (in 1 μL). All of the “MEK” (Line 2) was added to thereactions flasks, as well as 10% of “ss-MAIB Solution” (Line 3) and“ss-Monomer Mixture” (Line 4).

9) The temperature was set at 80° C. and stirring was set at 400 rpm.

10) Once the reaction mixture reached 79° C., semicontinuous addition ofthe remaining “Monomer Mixture” (line 4) and “MAIB Solution” (line 3)was begun, and added over the next six hours in a series of 100 equalvolume injections while maintaining an internal temperature of 80° C.

11) Heating of the reaction mixture at 80° C. was continued for anadditional two hours past the end of the feed.

12) The reactor vessels were left for cooling to room temperature andopened to collect solutions. The reaction mixtures were concentrated sothat half of the solvent (MEK) is removed.

Example to Prepare Polymers with a Nominal Composition N1/P1/Q1(50/35/15) at Different Molecular Weights Using CTA-HT3 as ControllingAgent in a Library Format (116964)

Stock Solutions are prepared in an inert atmosphere and are:

1) “Monomer Mixture”: 16.506 g N1+15.466 g P1+5.846 g Q1+80 mL MEK

2) “MAIB Solution”: 2.388 g MAIB+30 mL MEK to get 32.967 mL of stocksolution.

3) “CTA Solution”: 1.300 g CTA-H-T-3+3 mL MEK to get 4.615 mL of stocksolution.

4) “MEK” (pure): 11.776 mL MEK

Reaction:

5) All of “CTA Solution” (ss-CTA-HT3) were preliminary added to 8reactor vessels of a Semi-Continuous Parallel Pressurized Reactor (Table5, ss-CTA-HT3).

6) Three individuals lines (2, 3 and 4) were respectively primed withsolvent (MEK), ss-MAIB and the methacrylate stock solution(ss-methacrylate) before sealing the reactor vessels.

7) The reactor vessels were degassed by a pressurization, pressurerelieve and backfilling under inert-cycles with high purity argon.

8) Solutions dispensed in each of the 8 reactor vessels are identifiedin table 5 (in microliters). All of the “MEK” (Line 2) was added to thereactor vessels, as well as 10% of ss-MAIB (Line 3) and“ss-methacrylate” (line 4).

9) The temperature was set at 80° C. and stirring was set at 400 rpm.

10) Once the reaction mixture reached 79° C., the semicontinuousaddition of the remaining “Monomer Mixture” (line 4) and “MAIB Solution”(line 3) was begun, and added over the next six hours in a series of 100equal volume injections while maintaining an internal temperature of 80°C.

11) Heating of the reaction mixture at 80° C. was continued until theend of the reaction.

12) The reactor vessels were left for cooling to room temperature andopened to collect solutions. The reaction mixtures were concentrated byremoving half of the solvent (MEK). Physical results of isolated polymerare shown in Tables 5 and 6 for 116964.

Preparation of Sample B 15 (11695004) with a Nominal CompositionN1/Q1/P6 (45/15/40) Targeting Mw=8,500 g/mol at 100% Conversion UsingCTA-HAB 1 as Controlling Agent in a Library Format

Stock Solutions prepared for the whole library 116950 involving B15

1) Monomer Mixture “ss-B15”: 3.82963 g N1+1.357287 g Q1+2.576706 g P6 in30 mL MEK.

2) “MAIB Solution”: 1.906579 g MAIB+45 mL MEK

3) “CTA Solution”: 284.118 mg CTA-H-AB-1+2 mL MEK

4) “MEK” (pure): 55.559 mL MEK

For vial 11695004, volumes to be dispensed were:

1) “ss-B15”: 6577.054 uL

2) “MAIB Solution”: 433.4494 uL

3) “CTA-HAB1”: 341.8227 uL

4) “MEK”: 647.6735 uL

Reaction conditions:

1) CTA Solutions (341.8 uL of “CTA-HAB1” in vial 4) were preliminaryadded to reactor vessels of Symyx's Semi continuous ParallelPolymerization Reactor (SCPPR).

2) Lines of the reactor were respectively primed with solvent, MAIB andmethacrylate solutions before sealing.

3) Vials are degassed by a pressurization, pressure relieve andbackfilling under inert-cycles with high purity argon.

4) Solutions were dispensed for the synthesis of 11695004 as identifiedabove. All of the “MEK” (647.6735 uL) was added to the reaction flask,as well as 10% of “MAIB Solution” (43.34 uL) and 10% of “MonomerMixture” (657.70 uL).

5) The temperature was set at 80° C., stirring was set at 400 rpm andreactors pressurized at 120 psi.

6) Once the reaction mixture reached 79° C., the semi continuousaddition of the remaining “Monomer Mixture” (line 4) and “MAIB Solution”(line3) was begun, and added over the next six hours while maintainingan internal temperature of 80° C.

7) Heating of the reaction mixture at 80° C. was continued for anadditional two hours past the end of the feed.

8) The reactors were left for cooling to room temperature and opened tocollect solutions.

9) After precipitation into isopropanol, about 880 mg of polymer wascollected (70% of yield after precipitation). Narrow calibration GPCgave Mw # 7,000 g/mol and PDI # 1.17. Conventional GPC gave Mw # 7,000g/mol and PDI # 1.29.

Polymerization Processes (G) for Tables 1, 2, 3, 4, 5 and 6:

1: 10% of radical source (ss MAIB, V601, MAIB) and 10% of monomer loadedinitially, 3 hours of feeding (100 injections) followed by 6 hours ofreaction

2: 10% of radical source (ss-MAIB, V601) and 10% of monomer loadedinitially 6 hours of feeding (100 injections) followed by 2 hours ofreaction

3: 10% of radical source (ss-MAIB, V601) and 10% of monomer loadedinitially followed by 5 hours of feeding (100 injections) only

4: 10% of radical source (ss-MAIB, V601) and 10% of monomer loadedinitially followed by 12 hours of feeding (100 injections) only

5: 10% of radical source (ss-MAIB, V601) and 10% of monomer loadedinitially 3 hours of feeding (100 injections) followed by 2 hours ofreaction

6: polymers were dissolved in MEK (20% w/w) in the presence of 4equivalents of radical source (AIBN, Lauroyl peroxide or MAIB) andheated at 85° C. for 1 h. Polymer is then purified by precipitation intoisopropanol.

7: batch process polymerization for 3 h at 80 C

8: feeding was performed over a period of 7 h followed by an additionalhour of reaction.

9: batch process polymerization for 8 h at 80 C

10: feeding was performed over a period of 8 h

11: 10% of radical source (ss-MAIB) and 10% of monomer loaded initially,9 hours of feeding (100 injections) followed by 3 hours of reaction

12: 10% of radical source (ss-MAIB) and 10% of monomer loaded initiallyfollowed by a continuous feeding (100 injections) during 8 hours.

13: 10% of radical source (ss-MAIB) and 10% of monomer loaded initially,15 hours of feeding (100 injections) followed by 5 hours of reaction

14: 10% of radical source (ss-MAIB) and 10% of monomer loaded initially,followed by a continuous feeding (100 injections) during 20 hours.

15: 10% of radical source (ss-MAIB) and 10% of monomer loaded initially,3 hours of feeding (100 injections) followed by 1 hour of reaction

TABLE 1 Polymerization Process Conditions Targeted MAIB/ Mw at TargetedReference Sample # CTA CTA Cleavage Temperature 100% Process composition(A) (B) (C) (D) (E) (F.) conversion (G) (H) 11692711 A4 HT7 0.3 — 607000 1 N2: 55 P5: 35 Q3: 10 11692712 A5 HT7 — lauroyl 80 7000 6 N2: 55peroxide P5: 35 Q3: 10 11693911 A1 HT3 0.5 — 80 6000 2 N1: 50 P1: 35 Q1:15 11694211 A2 HT3 — lauroyl 80 6000 6 N1: 50 peroxide P1: 35 Q1: 1511342201 A2b HT3 — MAIB 65 6000 6 N1: 50 P1: 35 Q1: 15 11342202 A2c HT3— AIBN 80 6000 6 N1: 50 P1: 35 Q1: 15 11693316 B4 HAB1 0.3 — 80 12000 3N2: 55 P5: 35 Q3: 10 11692003 B6 HT7 — lauroyl 65 20000 6 N2: 55peroxide P5: 35 Q3: 10 11693320 B6b HAB1 0.3 — 65 20000 1 N2: 55 P5: 35Q3: 10 11694001 B1 HT3 0.3 — 80 3000 4 N1: 50 P1: 35 Q1: 15 11693012 B3HT7 — lauroyl 80 9000 6 N1: 50 peroxide P1: 35 Q1: 15 11691323 B3b HT30.5 — 80 10000 2 N1: 50 P1: 35 Q1: 15 11691305 B3c HT3 0.1 — 80 10000 5N1: 50 P1: 35 Q1: 15 11694501 B7 HT3 0.5 — 80 2400 2 N1: 60 P1: 4011694507 B8 HT3 0.5 — 80 6700 2 N1: 60 P1: 40 11694515 B9 HT3 0.5 — 8011000 2 N1: 60 P1: 40 11695307 B9b HT3 0.5 — 80 13000 2 N1: 60 P1: 4011695308 B9c HT3 0.5 — 80 15000 2 N1: 60 P1: 40 11695706 B10 HT3 0.5 —80 12000 2 N1: 60 P1: 40 11695010 B11 HT3 0.5 — 80 5500 2 N1: 50 P2: 13P1: 37 11695012 B12 HT3 0.5 — 80 8500 2 N1: 50 P2: 13 P1: 37 11695701B12b HT3 0.5 — 80 9000 2 N1: 50 P2: 13 P1: 37 11695014 B13 HT3 0.5 — 805500 2 N1: 60 P2: 10 P1: 30 11695015 B14 HT3 0.5 — 80 5000 2 N1: 50 P2:40 Q1: 10 11695004 B15 HAB1 0.4 — 80 7000 2 N1: 50 P6: 40 Q1: 1010639564 HT7 0.2 — 65 10000 7 N2: 55 P5: 35 Q3: 10 11690741 HT7 0.2 — 6510000 8 N2: 55 P5: 35 Q3: 10 10639561 HT7 0.2 — 65 10000 7 N1: 50 P1: 35Q1: 15

TABLE 2 Physical Properties for Polymeric resins of Table 1 ConventionalRapid GPC calibration GPC ¹H NMR Mw PDI Mw PDI composition 11692711 69001.35 7000 1.30 N2: 51 P5: 37 Q3: 12 11692712 7800 1.34 7500 1.25 N2: 51P5: 38 Q3: 11 11693911 6200 1.5 6300 1.32 N1: 46 P1: nd Q1: nd 116942117400 1.29 7600 1.18 N1: 46 P1: nd Q1: nd 11342201 6800 1.35 7404 1.23N1: 46 P1: nd Q1: nd 11342202 6500 1.36 7156 1.23 N1: 46 P1: nd Q1: nd11693316 4300 1.22 4500 1.16 N2: 50 P5: 38 Q3: 12 11692003 12500 1.4512400 1.28 N2: 49 P5: 38 Q3: 13 11693320 10500 1.53 11000 1.24 N2: 49P5: 38 Q3: 13 11694001 3500 1.25 3600 1.31 N1: 50 P1: nd Q1: nd 116930128700 1.4 8700 1.22 N1: 48 P1: nd Q1: nd 11691323 7800 1.4 7800 1.28 N1:47 P1: nd Q1: nd 11691305 10300 1.51 10500 1.27 N1: 46 P1: nd Q1: nd11694501 3100 1.3 3500 1.27 N1: 58 P1: 42 11694507 6500 1.57 6300 1.31N1: 59 P1: 41 11694515 9100 1.67 9100 1.39 N1: 59 P1: 41 11695307 89001.35 9000 1.31 N1: 58 P1: 42 11695308 10100 1.44 10000 1.28 N1: 59 P1:41 11695703 11700 1.75 12300 1.39 N1: 59 P1: 41 11695010 5000 1.4 55001.19 N1: nd P2: nd P1: nd 11695012 7200 1.47 7200 1.29 N1: nd P2: nd P1:nd 11695701 8800 1.6 9000 1.31 N1: nd P2: nd P1: nd 11695014 5300 1.455500 1.28 N1: nd P2: nd P1: nd 11695015 4500 1.39 5300 1.25 N1: nd P2:nd Q1: nd 11695004 7000 1.29 7000 1.17 N1: 43 P6: nd Q1: nd 11692005 ndnd 8100 1.14 N1: 46 P1: nd Q1: nd 11691705 6500 1.26 7100 1.14 N2: 49P5: 38 Q3: 13 10639564 nd nd 3500 1.27 N2: 59 P5: 32 Q3: 9 11690741 ndnd 4600 1.13 N2: 52 P5: 36 Q3: 13 10699561 nd nd 36000 1.6 N1: nd P1: ndQ1: nd nd = not determined

Size Exclusion Chromatography was performed using an automated rapid GPCsystem for rapid screening (see WO 99/51980, incorporated herein byreference). An automated conventional GPC system was utilized forsecondary screening. In the current setup N,N-dimethylformamidecontaining 0.1% of trifluoroacetic acid was used as an eluent for therapid GPC system whereas THF was used for the conventional system andpolystyrene-based columns. All of the molecular weight results obtainedare relative to linear polystyrene standards. NMR was carried out usinga Bruker spectrometer (300 MHz) with CDCl₃ (chloroform-d) as solvent.

Rapid calibration GPC utilized 3 columns (PLgel, 5 μm Mixed D 300×7.5mm) THF 1.0 mL/min; detectors RI, UV 220 and 290 nm; Standard forcalibration: EsiCal PS-2

Conventional calibration GPC utilized 3 columns (PLgel, 10 μm Mixed-B300×7.5 mm) THF 1.0 mL/min; detectors RI, UV 280 nm; Standard forcalibration: EsiCal PS-1

TABLE 3 Volume of stock solutions (ss) in microliters, dispensed in anarray format: Preparation of Polymeric Resins via Semi-continuousparallel polymerization reactions (SCPPR) 2-butanone ss-MAIBss-methacrylate Vial Line 2 Line 3 Line 4 ss-CTA-HT3 1 88.36388 1364.5636171.411 375.6622 2 958.4765 682.2815 6171.411 187.8311 3 1248.514454.8543 6171.411 125.2207 4 1426.999 314.8991 6171.411 86.69128 588.36388 1364.563 6171.411 375.6622 6 958.4765 682.2815 6171.411187.8311 7 1248.514 454.8543 6171.411 125.2207 8 1426.999 314.89916171.411 86.69128 9 88.36388 1364.563 6171.411 375.6622 10 958.4765682.2815 6171.411 187.8311 11 1248.514 454.8543 6171.411 125.2207 121426.999 314.8991 6171.411 86.69128 13 88.36388 1364.563 6171.411375.6622 14 958.4765 682.2815 6171.411 187.8311 15 1248.514 454.85436171.411 125.2207 16 1426.999 314.8991 6171.411 86.69128 17 88.363881364.563 6171.411 375.6622 18 958.4765 682.2815 6171.411 187.8311 191248.514 454.8543 6171.411 125.2207 20 1426.999 314.8991 6171.41186.69128 21 88.36388 1364.563 6171.411 375.6622 22 958.4765 682.28156171.411 187.8311 23 1248.514 454.8543 6171.411 125.2207 24 1426.999314.8991 6171.411 86.69128

TABLE 4 polymerization results with library 116959 at 80° C.Polymerizations were all performed at 80° C., initial molar ratioMAIB/CTA = 0.5, CTA-H-T-3 as a controlling agent with a targetedcomposition in molar percent of 50% N1, 35% P1 and 15% Q1. 11698401 and11698402 were performed in schlenk tubes as a batch process. Conversionwas estimated by Raman Spectroscopy (measuring the disappearance ofvibration peak at 1600 cm⁻¹) and by ¹H NMR for 11698401 and 11698402 (%of NML). Reference Process Mw Conversion (A) (G) targeted (%) Mw PDi11698401 9 3,000  90* 4400 1.62 11698402 9 9,000  85* 8800 1.57 116959012 3,000 86 3800 1.34 11695902 2 6,000 85 6000 1.35 11695903 2 9,000 817800 1.33 11695904 2 12,000 70 10500 1.3 11695905 10 3,000 92 3600 1.3611695906 10 6,000 85 5700 1.32 11695907 10 9,000 75 7100 1.34 1169590810 12,000 82 9700 1.27 11695909 11 3,000 94 3900 1.59 11695910 *11695911 * 11695912 * 11695913 4 3,000 90 4670 1.61 11695914 *11695915 * 11695916 4 12,000 43 10720 1.41 11695917 13 3,000 97 35001.33 11695918 13 6,000 97 6100 1.35 11695919 13 9,000 97 8000 1.3911695920 13 12,000 92 10800 1.38 11695921 14 3,000 95 4300 1.4 1169592214 6,000 93 5700 1.35 11695923 14 9,000 83 7200 1.36 11695924 **Mechanical failure, no result 11698401 and 11698402 were prepared in abatch process

TABLE 5 Volume of the stock solutions (in uLdispensed in an array formatusing SCPPR. MEK ss-MAIB ss-methacrylate Vial Strip Line 2 Line 3 Line 4ss-CTA-HT3 1 1 6.904158 1023.422 6486.679 482.9943 2 760.1124 511.71116486.679 241.4971 3 1011.182 341.1407 6486.679 160.9981 4 1165.686236.1744 6486.679 111.4602 17 3 6.904158 1023.422 6486.679 482.9943 18760.1124 511.7111 6486.679 241.4971 19 1011.182 341.1407 6486.679160.9981 20 1165.686 236.1744 6486.679 111.4602

TABLE 6 polymerization results with library 116964 AT 80° C.Polymerization were all performed at 80° C., initial molar ratioMAIB/CTA = 0.5, CTA-H-T-3 as a controlling agent with targetedcomposition in molar percent of 50% N1, 35% P1 and 15% Q1. Conversionwas estimated by Raman Spectroscopy (measuring the disappearance ofvibration peak at 1600 cm⁻¹). Symyx Reference Process Mw Conversion (A)(G) targeted (%) Mw PDi 11695901 15 3,000 86 3800 1.33 11695902 15 6,00087 6100 1.35 11695903 15 9,000 85 8400 1.37 11695904 15 13,000 80 105001.37 11695917 2 3,000 97 3740 1.29 11695918 2 6,000 97 6200 1.3011695919 2 9,000 97 8200 1.31 11695920 2 13,000 95 11200 1.33

For more information regarding general synthesis utilizing asemicontinuous polymerization reactor (SCPPR), see for example, U.S.patent application Ser. No. 09/873,176, filed on Jun. 1, 2001 entitled“Parallel Semicontinuous or Continuous Reactors”, the contents of whichare incorporated herein by reference in their entirety.

Although the present invention has been described with reference topreferred embodiments, persons skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

1. A polymer comprising the formula:[A]_(x)[B]_(y)[C]_(z) wherein A, B and C are each individually one of

wherein x is between about 0 and about 200 inclusive, y is between about1 and about 200 inclusive and z is between about 1 and about 200inclusive, provided B≠C wherein the polymer is prepared by a living freeradical process (LFRP) in the presence of a chain transfer agent (CTA)having the formula:

wherein R¹ is any group that can be expelled as its free radical form inan addition-fragmentation reaction; R² and R³ are each independentlyselected from the group consisting of hydrogen, hydrocarbyl, substitutedhydrocarbyl, heteroatom-containing hydrocarbyl, and substitutedheteroatom-containing hydrocarbyl, and combinations thereof, andoptionally R² and R³ together to form a double bond optionallysubstituted alkenyl moiety; R⁴ is selected from the group consisting ofhydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containinghydrocarbyl, and substituted heteroatom-containing hydrocarbyl, andcombinations thereof; and optionally, R⁴ combines with R² and/or R³ toform a ring structure, with said ring having from 3 to 50 non-hydrogenatoms; and D is either sulfur, selenium or tellurium.
 2. The polymer ofclaim 1, wherein x is at least
 1. 3. The polymer of claim 1, wherein thepolydispersity index is less than 1.7.
 4. The polymer of claim 1,wherein the polydispersity index is between about 1.2 to about 1.4. 5.The polymer of claim 1, wherein the M_(w) is between about 3,000 andabout 20,000.
 6. The polymer of claim 1, wherein the M_(w) is betweenabout 3,000 and about 10,000.
 7. The polymer of any one of claims 1-6,wherein A, B and C are each individually one of

and x is at least
 1. 8. The polymer of any one of claims 1-6, wherein A,B and C are each individually one of

and x is at least one.
 9. The polymer of claim 8, wherein the formula is


10. The polymer of claim 9, wherein the M_(w) is between about 3,000 and10,000.
 11. The polymer of claim 9, wherein the polydispersity index isabout 1.3.
 12. The polymer of any one of claims 1-6, wherein A, B and Care each individually one of

and x is at least one.
 13. The polymer of claim 12, wherein the formulais


14. The polymer of claim 13, wherein the M_(w) is between about 3,000 toabout 12,000.
 15. The polymer of claim 13, wherein the polydispersityindex is between about 1.1 and about 1.2.
 16. The polymer of any one ofclaims 1-6, wherein A, B and C are each individually one of

and x is at least one.
 17. The method of claim 16, wherein the formulais


18. The method of claim 17, wherein the M_(w) of the polymer is betweenabout 3,000 to about 12,000.
 19. The method of claim 17, wherein thepolydispersity index of the polymer is between about 1.1 and about 1.2.20. The polymer of any one of claims 1-6, wherein the terminal endposition includes a thiocarbonylthio moiety.
 21. The polymer of any oneof claims 1-6, wherein the terminal end position includes a terminationgroup having the formula

wherein R′ is CN or COOMe.